How to Build a Berm for Landscaping

by Amelia Allonsy

Landscaping berms provide privacy, break up large areas of flat land and showcase plants.

Perfectly flat land might make it easy to mow your lawn, but flat land lacks the visual interest of a rolling landscape. Berms -- small, elongated hills with a gradual slope -- add height so you can showcase plants on a raised platform. You can use a berm to create a privacy screen with small trees, to divide sections of your yard or simply to add dimension to your outdoor space. Berms look most natural when they are only 2 to 3 feet tall and should be four to six times as long as they are wide.

1

Sketch the design of the berm to scale on graph paper before committing to the design so you can make sure you have enough room to build a berm that looks natural in your space. Berms to showcase trees should slope out horizontally 5 to 7 feet for every 1 foot of height; berms for small plants can thrive on steeper slopes of about 3 to 4 feet of run for every 1 foot of rise. The peak of the berm should be positioned closer to one end instead of in the center of the berm and the top of the berm should be flat to prevent water from running off the sides of the slope. Rather than designing a perfect oval, you can have undulating tapered edges, multiple peaks or even a crescent shape.

2

Lay out the design for the berm on the ground with garden hoses; the garden hoses flex easily so you can achieve curves and make design changes before fully committing to a design. After you are satisfied with the shape of the berm, you can transfer the outline to the turf with landscaping spray paint.

3

Remove the sod layer from inside the marked outline, using a spade or sod cutter to cut through the turf. You can leave the turf in place, if desired, but carving out the grass makes it easier to see your design as you build up the berm.

4

Add clean fill dirt to the inside of the berm design perimeter to build up the bulk of the berm. Spray the mound with a garden hose to moisten the soil and pack the soil down tightly. The fill dirt should account for about half the total height of the finished berm; leave about 1 1/2 feet from the outline edges free of fill dirt to allow room for top soil. .

5

Cover the fill dirt with a few inches up to 1 foot of clay soil, depending on the total berm height in your plan. Make any final corrections in the berm shape with the clay layer. Although clay and fill dirt are not required, clay is often used because it sticks well and is less likely to erode after a heavy rain, which can affect the berm's shape.

6

Add topsoil over the clay layer to build up the remaining height for the berm.

7

Flatten the topsoil on top of the berm with a shovel so the berm doesn't form a pointed peak. Drag the topsoil with a bow rake down to the outer perimeter of the berm outline to achieve the necessary slope for the berm and smooth the edges. Pack the topsoil gently to hold it in place on the sides of the hill.

8

Place large flagstones and boulders throughout the berm to give the berm a more natural appearance. Bury one-third to one-half of each stone so the stones appear as natural fixtures on the hill.

9

Plant your choice of small trees, shrubs, perennial and annual flowers and groundcovers on the berm as soon as possible so the roots can take hold and anchor the soil in place on the sides of the slope. The top of the berm is a great location for showcasing short plants that often get lost when planted on flat ground. You can plant several trees at the top of the berm, but avoid planting in a straight line, which can appear unnatural. Medium-height plants and groundcovers work to fill in space on the sides of the slope and helps to keep soil from washing down the slope.

10

Add a 2- to 3-inch layer of mulch around plants on the berm. Mulches with irregular shapes, such as shredded bark, work best because the long pieces tend to lock together to resist washing down the slope.

Things You Will Need

Graph paper

Garden hoses

Landscaping spray paint

Spade or sod cutter

Shovel

Fill dirt

Clay soil

Topsoil

Flagstones and boulders, optional

Assorted plants

Shredded bark mulch

Tip

Most of the shaping is done with the fill dirt and clay layers of the berm. The top soil simply covers the framework for the berm.

You can build the entire berm from topsoil if you wish, but topsoil is much more expensive than fill dirt. If you plan to plant trees at the top of the berm, skip the fill dirt and clay layers to provide a berm depth that can accommodate deep tree roots. Many smaller plants only require 4 to 8 inches of soil for healthy root expansion, so the fill dirt saves money on topsoil that would go unused.

When you choose to build a berm with wavy edges instead of a simple oval design, use only gradual curves so you can easily achieve the wavy design with sloping soil.

About the Author

Based in West Virginia, Amelia Allonsy began writing in 2004. Her specializations include cooking, baking, gardening, and cultural topics. She received her Bachelor's degree from West Virginia University. Her work has been published by the "San Francisco Chronicle" and on other websites.

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